Protection apparatus for implantable medical device

ABSTRACT

A method and apparatus for protecting an electronic implantable medical device prior to it being implanted in a patient&#39;s body. The apparatus affords protection against electronic component damage due to electrostatic discharge and/or physical damage due to improper handling. The apparatus is comprised of a circuit board having conductive surface means for receiving and releasably grasping the electrodes of the medical device to support the device&#39;s housing proximate to the surface of the circuit board. First and second conductive paths are formed on the circuit board extending between the first and second conductive surfaces for shunting electrostatic discharge currents to prevent such currents from passing through the device&#39;s electronic circuitry. The respective shunt paths include oppositely oriented diodes, preferably comprising diodes which emit light (i.e., LEDs) when current passes therethrough. Additionally, means are provided to enable functional testing of the medical device.

This application is a divisional of U.S. patent application Ser. No.10/454,871, filed Jun. 3, 2003, which is a continuation-in-part of U.S.patent application Ser. No. 10/420,070, filed Apr. 17, 2003, which inturn is a continuation-in-part of U.S. Pat. No. 6,551,345.

FIELD OF THE INVENTION

This invention relates generally to a method and apparatus for use withan electronic implantable medical device for protecting the device fromphysical and/or electrostatic discharge damage prior to medicallyimplanting the device in a patient's body. Moreover, preferredembodiments of the invention afford the ability to functionally test thedevice without removing it from its sterilized shipping container priorto implantation.

BACKGROUND OF THE INVENTION

Many types of electronic medical devices are known which are intendedfor implantation in a patient's body. Although these devices vary widelyin design, they typically include a housing containing electroniccircuitry connected to two or more electrodes which extend exteriorlyfrom the housing (or one or more electrodes when the housing is theother electrode). The circuitry can, for example, include a functionalcircuit (e.g., a pulse generator), a power supply circuit (e.g.,rechargeable battery), and a transceiver for wirelessly communicatingwith an external controller. Implantable medical devices of this sortare useful in a variety of applications for stimulating muscle or nervetissue and/or monitoring body parameters. See, for example, U.S. Pat.Nos. 6,164,284; 6,185,452; 6,208,894; 6,315,721; and 6,472,991; whichprimarily relate to such devices that are battery powered, each of whichis incorporated by reference herein in their entirety. Also see, forexample, U.S. Pat. Nos. 5,193,539; 5,193,540; 5,312,439; 5,324,316; and5,405,367; which primarily relate to such devices that are RF powered,each of which is incorporated by reference herein in their entirety.

To minimize device failure and maximize device reliability, it isimportant that an electronic medical device be properly handled alongthe entire chain from manufacturing, through shipping and storage, andon to the medical procedure for implanting the device in a patient'sbody. For example, improper handling can subject the device to physicaldamage and/or component damage due to electrostatic discharge (ESD).

SUMMARY OF THE INVENTION

The present invention is directed to a method and apparatus forprotecting an electronic implantable medical device prior to it beingimplanted in a patient's body. More particularly, a method and apparatusin accordance with the invention affords protection to the medicaldevice from just after manufacture to just prior to implantation.Protection is afforded against electronic component damage due toelectrostatic discharge and/or physical damage due to improper handling.

Embodiments of the invention are particularly valuable when used withsmall fragile medical devices which often comprise an electronic circuithousing having an axial dimension of less than 60 mm and a lateraldimension of less than 6 mm. The housing typically contains electroniccircuitry which is electrically connected to first and second electrodeswhich extend exteriorly from the housing. See, for example, U.S. Pat.Nos. 6,164,284; 6,185,452; 6,208,894; 6,315,721; and 6,472,991; whichprimarily relate to such devices that are battery powered, each of whichis incorporated by reference herein in their entirety. Also see, forexample, U.S. Pat. Nos. 5,193,539; 5,193,540; 5,312,439; 5,324,316; and5,405,367; which primarily relate to such devices that are RF powered,each of which is incorporated by reference herein in their entirety.

A preferred apparatus in accordance with the invention is comprised of acircuit board having first and second connective surfaces integral tothe circuit board. The connective surfaces are configured using elasticO-rings to receive and releasably grasp the electrodes of a medicaldevice housing to support the housing proximate to the surface of thecircuit board. First and second conductive paths are formed on thecircuit board extending between the first and second connective surfacesfor shunting electrostatic discharge currents to prevent such currentsfrom passing through the device's electronic circuitry. Preferably, therespective shunt paths include oppositely oriented diodes, preferablycomprising diodes which emit visual light (i.e., LEDs) when currentpasses therethrough.

In accordance with the invention, a medical device is preferably mountedin the protective apparatus as a late step in the device manufacturingprocess. The protection apparatus/device combination is then placed intoa shipping container. The combination remains engaged until the deviceis ready for medical implantation in a patient's body. The shippingcontainer preferably includes a transparent window through which thelight emitting diodes are visible.

In a preferred method in accordance with the invention, the medicaldevice is sterilized, e.g., using steam or ethylene oxide (ETO), afterbeing placed in the shipping container.

A significant feature of the invention allows the medical device to befunctionally tested while in the shipping container. More particularly,exemplary medical devices include (1) transceivers which permit wirelesscommunication of commands and data between an external controller andthe device electronic circuitry and (2) battery charging circuits whichextract energy from an external power source, e.g., via an alternatingmagnetic field, for charging a device battery. In accordance with theinvention, a medical device can be functionally tested while still inthe shipping container by transmitting a command or activation signal tothe device. If the device is functioning properly, it will respond in aparticular manner, as by outputting a sequence of pulses whosecharacteristics (e.g., frequency, pulse width, etc.) indicate properoperability. This output pulse sequence drives the protection apparatusLEDs which can be monitored to detect whether the device is operatingwithin specifications. Additionally, the device battery can be chargedwhile still in the shipping container by an external power source.

In a still further significant aspect of the present invention, a cutoutis provided in the circuit board to permit a wire loop from anoscilloscope, pulse generator, or the like, to pass through andinductively measure/induce the electrical input/output characteristicsof the medical device before implantation. A sealing pouch preferablyhas a conforming cutout to facilitate this test while maintaining themedical device in a sterilized environment. Alternatively and/oradditionally, a photodiode may be placed on the circuit board to emitnonvisual radiation that may be sensed by an external detectionapparatus to measure the electrical output characteristics of themedical device. Finally, the output characteristics of the medicaldevice may be measured using external capacitively coupled plates and/orone or more coils.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts the structure of an exemplary electronicimplantable medical device of the type intended for use with the presentinvention.

FIG. 2 is a block diagram generally representing the electroniccircuitry typically employed in the exemplary medical device of FIG. 1.

FIG. 3 schematically depicts the exemplary medical device of FIG. 1 usedin combination with a protection apparatus in accordance with thepresent invention.

FIG. 4 is an exploded isometric illustration depicting a protectionapparatus in accordance with the present invention.

FIG. 5 is an isometric illustration depicting a protection apparatus inaccordance with the present invention for accommodating a medical deviceto be protected.

FIG. 6 is an exploded isometric illustration depicting the manner ofplacing the protection apparatus and medical device into an exemplaryshipping container.

FIG. 7 is an isometric view depicting the protection apparatus andmedical device received in the exemplary shipping container and orientedso that the light emitting diodes (LEDs) of the apparatus are visiblethrough a container transparent window.

FIG. 8 is a block schematic diagram depicting how the medical device istested while in the exemplary shipping container.

FIGS. 9A and 9B show isometric views of the mounting of the medicaldevice on a planar surface having a pair of connective surfaces formaking electrical contact with the electrodes of the medical device anda pair of O-rings for retaining physical and electrical contact betweenthe medical device's electrodes and the circuit board's connectivesurfaces.

FIGS. 10A and 10B show isometric views of the mounting of the medicaldevice on a planar surface having a pair of connective surfaces formaking electrical contact with the electrodes of the medical device anda single O-ring for retaining physical and electrical contact betweenthe medical device's electrodes and the circuit board's connectivesurfaces.

FIG. 11 shows an isometric view of the circuit board and O-ring mountingapparatus of FIGS. 10A and 10B, additionally including a photodiode foremitting nonvisual radiation that can be externally monitored to testthe functionality of the medical device, e.g., while it is still withina sterilized container, e.g., a pouch.

FIG. 12 shows a simplified schematic diagram of additional embodimentsof the present invention that include the photodiode of FIG. 11 and/or acurrent loop path that may be used to emit an inductively coupled fieldto a loop connected to an oscilloscope probe or the like. Alternatively,a pulse generator of the like may be used to inductively emit a signalinto the loop on the circuit board and thus verify the functionality ofthe sensor mode circuitry in the medical device.

FIGS. 13A and 13B show the presence of the current loop path describedin reference to FIG. 12 with a cutout for allowing the oscilloscopeprobe loop to pass through.

FIGS. 14A, 14B, and 14C respectively show top, side and bottom viewscorresponding to the embodiment of FIGS. 13A and 13B sealed within asterile pouch having a compliant cutout formed thereon. Additionally,the use of an optional breakaway section is shown to remove the LEDportion and thus improve the functionality of the current loop path (byremoving interactions with the LED path).

FIG. 15 is a block schematic diagram depicting how the medical device istested while in the shipping container includes one or more of thefollowing techniques: sensing of nonvisual radiation from the photodiodeusing a photodetector and a transconductance amplifier, use of aninductively coupled current loop path (with an optional breakawaysection to electrically detach the LEDs), capacitive sensing of thecircuitry, inductive sensing of the circuitry (without the current looppath and cutout), and/or one or more switches, e.g., a single poledouble throw (SPDT) switch, to selectively connect the medical device'selectrodes to the LEDs and/or the inductively coupled current loop.

FIGS. 16A-16D are alternative embodiments of that previously shown inFIG. 10A wherein the connective surfaces are formed with slots to reduceeddy currents and thereby reduce signal loss to the implantable medicaldevice of the magnetic and/or electromagnetic signals while it is heldby the protection apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Attention is initially directed to FIG. 1 which schematically depicts anelectronic implantable medical device 20. The device 20 is intended tobe representative of a wide range of known electronic devices designedto be medically implanted in a patient's body for a variety ofapplications. For example only, such devices can be controlled toselectively stimulate muscle and nerve tissue and/or monitor and reportvarious body parameters. The exemplary device 20 is depicted ascomprising an elongate housing 22 defined by a peripheral wall 24enclosing an interior volume 26. The housing 22 can be variously shapedbut, for simplicity herein, it will be assumed to be cylindrical.Typically such implantable medical devices are small in size, e.g.,preferably having an axial dimension of less than 60 mm and a lateraldimension of less than 6 mm, and relatively fragile structurally. See,for example, U.S. Pat. Nos. 6,164,284; 6,185,452; 6,208,894; 6,315,721;and 6,472,991; which primarily relate to such devices that are batterypowered, each of which is incorporated by reference herein in theirentirety. Also see, for example, U.S. Pat. Nos. 5,193,539; 5,193,540;5,312,439; 5,324,316; and 5,405,367, which primarily relate to suchdevices that are RF powered, each of which is incorporated by referenceherein in their entirety. Reasonable care must be exercised in handlingthe devices 20 to prevent physical damage.

The exemplary device 20 is depicted as containing electronic circuitry30 within the interior volume 26. The circuitry 30 is connected betweenfirst and second electrodes 32, 34 which extend exteriorly from thehousing 22. The circuitry 30 typically includes sensitive electroniccomponents which can be permanently damaged by high currents which canbe caused, for example, by electrostatic discharge (ESD). Accordingly,as with many other electronic devices, it is advisable to exerciseappropriate care to avoid discharging high currents through thecircuitry 30. The present invention is primarily directed to a methodand apparatus as depicted in FIGS. 3-15, for protecting the device 20,from damage while being shipped, stored, and handled between a latemanufacturing stage and up to the time it is implanted in a patient'sbody.

FIG. 2 is a block diagram which generally depicts the functionalcomponents of typical electronic circuitry 30 employed in an implantablemedical device 20. More particularly, the electronic circuitry 30 isshown as comprising a power supply 38 which may include a rechargeablebattery or a capacitor (not shown). A charging circuit 40 is connectedto the power supply 38 for deriving energy from an external power sourceto charge the battery. For example only, the charging circuit 40 canrespond to an alternating, e.g., amplitude modulated or frequencymodulated, magnetic field or RF field to supply a charging current tothe power supply 38. The power supply 38 is depicted as supplying anoperating voltage to a transceiver circuitry 42 and a pulse generator44. The transceiver circuitry 42 is configured to communicate with anexternal controller (not shown) employing a suitable form of wirelesscommunication via path 43, typically radio communication. Commands anddata can be supplied via path 43 from the external controller to thetransceiver circuitry 42 for controlling or programming the pulsegenerator 44. The pulse generator 44 can in turn provide data to thetransceiver circuit 42 via path 45 for communication to the externalcontroller.

It should be understood that FIG. 2 is intended to only very generallydepict the functionality of the electronic circuitry 30 contained in thedevice 20. The method and apparatus of the invention to be describedherein, is useful in combination with a wide variety of medical devices20, e.g., muscle stimulators, neural stimulators, physiological sensors,pacemakers, etc.

Attention is now directed to FIG. 3 which depicts an electronicprotection circuit 60 externally connected between the device electrodes32, 34. The protection circuit 60 is comprised of first and second shuntpaths 62, 64 which each include a unidirectional current device, e.g., adiode. Shunt path 62 contains diode 66 oriented from electrode 32 toelectrode 34. Shunt path 64 contains diode 68 which is oppositelyoriented, i.e., from electrode 34 to electrode 32. The shunt paths 62and 64 operate to shunt current spikes which can be caused, for example,by electrostatic discharge around electronic circuitry 30. Thus, theshunt paths limit excessive currents and voltage rise across the medicaldevice 20.

As will be discussed hereinafter, the diodes 66, 68 preferably have anaudible or light generator associated therewith to indicate currenttherethrough. More specifically, preferred embodiments of the inventionare preferably implemented with light emitting diodes (LEDs). As will beunderstood hereinafter, it is preferable for the respective LEDs toproduce light of different colors so that the direction of current flowbetween electrodes 32 and 34 can be readily determined by an observer.

FIG. 4 depicts a preferred implementation of a protection apparatus 70in accordance with the present invention tailored for use with theexemplary cylindrical medical device 20. The apparatus 70 is comprisedof a substrate or circuit board 72 having an upper surface 74 and alower surface 76.

First and second spring contact clips 80, 82 are provided for mountingon the circuit board 72. Each clip is essentially comprised of a cradleportion 84 including spaced first and second resilient arms 86, 88. Thearms 86, 88, together with end finger 90, define a cradle for releasablyretaining an electrode 32, 34 of device 20. The cradle portion 84 iscantilevered by a shank portion 92 which extends to spaced contactfingers 94, 96 and to a post 98. The clips 80, 82 can be inexpensivelyformed by a stamping and bending operation.

The circuit board 72 has shunt path 62 formed on upper surface 74depicted as including path portion 100 and path portion 102. Pathportion 100 is comprised of a longitudinal leg 104 and a lateral leg106. Similarly, path portion 102 is comprised of a longitudinal leg 108and a lateral leg 110. The clips 80 and 82 are respectively mounted ontothe board 72 with the posts 98 extending into and electricallycontacting through plated apertures 114 and 116 in path legs 104 and108. The through plated apertures extend and are electrically connectedto a second shunt path 64 formed on the opposite lower surface 76 ofcircuit board 72. The shunt path 64 on the surface 76 can be shapedidentically to the shunt path 62 on upper surface 74 depicted in FIG. 4.The post 98 of clip 80 extending through the aperture 114 electricallyinterconnects the first ends of shunt paths 62 and 64. Similarly, thepost 98 of clip 82 extending through aperture 116 electricallyinterconnects the second ends of shunt paths 62 and 64. Each shunt pathincludes a diode as depicted in FIG. 4. More particularly, note that LED120 is configured to be surface mounted across legs 106 and 110 of shuntpath 62 on board surface 74. Similarly, LED 122 is intended forcorresponding surface mounting in shunt path 64 on board surface 76.Alternatively, LEDs 120, 122 may be mounted on the same surface of thecircuit board 72.

FIG. 5 shows the medical device 20 accommodated in the clips 80 and 82and with the LEDs 120, 122 being mounted on opposite surfaces 74 and 76of circuit board 72. In accordance with the invention, the device 20 ismounted into the clips 80, 82 in a late stage of the manufacturingprocess of device 20. Thereafter, the mated protection apparatus 70 andmedical device 20 are placed in a shipping container 140, as depicted inFIG. 6. Shipping container 140 can be inexpensively formed of moldedplastic, and preferably includes a cavity 142 shaped and dimensioned toaccommodate the mated protection apparatus 70 and medical device 20. Inplacing the mated combination in the cavity, circuit board 72 should beoriented so that the LEDs 120 and 122 face upwardly. A transparent sheet150 covers the cavity 142, to define a window through which the LEDs 120and 122 are visible as depicted in FIG. 7.

It is intended that the protection apparatus 70 and medical device 20remain mated together in the shipping container 140 for the fullduration of its shelf life from the manufacturing stage to just prior tomedically implanting the device 20 in a patient's body. After the matedprotection apparatus and medical device 20 are placed into the shippingcontainer 140 and the cavity 142 sealed by transparent sheet 150, thedevice 20 is preferably sterilized using a known gas, e.g., ethyleneoxide (ETO), or steam process. For its entire life between manufacturingand implantation, the protection apparatus 70 will protect the medicaldevice from electronic component damage attributable to electrostaticdischarge (ESD). Moreover, the apparatus 70 protects device 20 againstphysical damage because it is firmly retained by spring clips 80, 82mounted on the substantially rigid circuit board 72.

In accordance with the present invention, the device 20 is preferablyfunctionally tested while still in its shipping container 140. Moreparticularly, as depicted in FIG. 8, an external power source 160 isable to charge the on-board device battery via the aforementionedcharging circuit 40 by generating an appropriate field, e.g.,alternating magnetic field, in close proximity to the device 20. Thepower source 160 can be similar or identical to the power sourcenormally used to charge the battery after the device is implanted in apatient's body. Similarly, an external controller 164 can be used toprovide commands and receive data from the medical device 20 while it isstill contained within the shipping container 140. In a particularlyuseful procedure, the controller 164 is able to wirelessly communicate acommand or activation signal to the device 20, e.g., via an RF signal.The controller 164 can be similar or identical to a controller utilizedby the patient or by a medical practitioner to program the device 20after implantation in the patient's body. The procedure depicted in FIG.8 contemplates that the controller 164 provides an activation signal tothe medical device 20 while it is still in the shipping container 140.The electronic circuitry of the device 20 is designed to respond to theactivation signal to cause pulse generator 44 to output a known pulsesequence between electrodes 32 and 34. This pulse sequence will causeLEDs 120 and 122 to illuminate in accordance with a pattern having knowncharacteristics (e.g., frequency, pulse width, etc.). The activity ofthe LEDs 120 and 122 can be monitored by monitor 168 to determinewhether the device 20 is operating properly. For example, if the device20 is configured to generate monophasic pulses, one LED will “brightly”light during generation of each pulse and the other LED will “dimly”light during recharge of the pulse generator 44. Alternatively, if thedevice 20 is configured to generate a biphasic pulse, the intensity ofthe light emitted from each LED will be approximately the same.

Thus, it will be appreciated that the protection apparatus 70 inaccordance with the present invention offers both electrical andphysical protection of the device 20 during shipping and handling, andfacilitates the testing of the device prior to it being medicallyimplanted in a patient's body.

It is important that medical devices intended for implantation in apatient's body be biocompatible, i.e., that they employ materials whichdo not produce deleterious effects on the living tissue. Thisrequirement dictates a choice of appropriate biocompatible materials. Inorder to avoid compromising biocompatibility, it is preferable that thecontact clips 80, 82 which physically contact the electrodes 32, 34 ofthe device 20 also be formed of an appropriate biocompatible material,e.g., platinum.

FIGS. 9A and 9B show isometric views of the mounting of the medicaldevice 20 on a planar surface 200 having a pair of connective surfaces202, 204 for making electrical contact with the electrodes 32, 34 of themedical device 20 and a pair of O-rings 206, 208 (preferably formed frommedical grade silicone) for physically retaining and maintainingelectrical contact between the medical device's electrodes 32, 34 andthe circuit board's connective surfaces 202, 204. In this embodiment,the use of O-rings 206, 208 functionally replace the previouslydescribed use of clips 80, 82 while further minimizing any potential fordamage to protective gloves worn by medical practitioners when workingwith the sterilized and packaged medical device 20. The O-rings 206, 208are easily rolled onto the ends of the circuit board 72 until they holdthe medical device 20 into contact with the connective surfaces 202,204. Since the package must be subject to high temperatures forsterilization purposes, the planar surface 20, e.g., circuit board 72,is formed of polyimide or like material that can withstand thetemperatures associated with sterilization. The connective surfaces arepreferably formed from a biocompatible material, e.g., platinum or goldplated nickel on copper to provide a surface that will minimizeelectrical resistance to the medical device's electrodes whilemaintaining biocompatible safety should the gold or platinum slough offonto the electrodes 32, 34. FIG. 9B, in particular, shows two optionalmeans that may be used to stabilize the position of the medical device20 on the connective surfaces. In this example, connective surface 202′is shown with a recess, e.g., a concave portion, and connective surface204′ is shown with a notched portion, each of which are exemplary ofoptional techniques for stabilizing the medical device's position.Clearly, each of these techniques could be used on both ends of themedical device and the use of different techniques for each electrode isprimarily for illustrative purposes to minimize the number of providedfigures.

FIGS. 10A and 10B (a variation of that already shown and described inrelation to FIGS. 9A and 9B) show isometric views of the mounting of themedical device 20 on a planar surface 200 having a pair of connectivesurfaces 202, 204 for making electrical contact with the electrodes 32,34 of the medical device 20 with a single O-ring 210 for retainingphysical and electrical contact between the medical device's electrodesand the circuit board's connective surfaces 202, 204. In thisembodiment, the circuit board 72 is formed with a pair of opposingretaining lips 212, 214 for retaining/capturing opposing ends of theO-ring 210. In operation, the O-ring 210 is typically initially capturedby the two retaining lips 212, 214 and when the medical device 20 isavailable it is slipped between the O-ring 210 and the circuit board 72from the outside end 216 of the circuit board 72 until its electrodes32, 34 line up with the connective surfaces 202, 204. Due to therelatively large size of the connective surfaces 202, 204 to theelectrodes 32, 34, this positioning is easily performed. Optionally, astop may be placed on connective surface 204 at location 218 to blockfurther inner movement of the medical device 20 during insertion intothe protection apparatus 70′ (see FIG. 10A). Alternatively, the medicaldevice 20 may be placed on the circuit board 72 and the single O-ring210 may be stretched and captured between the two retaining lips 212,214. Functionally, e.g., as pertaining to protection and test features,the apparatus described in relation to FIGS. 9A, 9B, 10A, and 10Bperforms as previously described in relation to FIGS. 4 and 5.

FIGS. 3-8, 10A and 10B, primarily show a protection apparatus whoseoutput drivers may also be functionally tested (generally in response toreceived communication signals) by visually (or automatically, seemonitor 168 in FIG. 8) monitoring the response of its LEDs 120 and 122when the medical device 20 is commanded to generate stimulation pulses.While this is an effective functional test, its capability to measureactual performance characteristics, e.g., the milliamp output, of themedical device 20 is limited. Accordingly, FIGS. 11-15 are primarilydirected to alternative embodiments that additionally provide thecapability to measure, albeit, indirectly the performancecharacteristics of the medical device 20 prior to implantation. Therequirement to indirectly measure these characteristics is dictated bythe requirement that the medical device 20 be maintained within asterile package before implantation. The description of varioustechniques follows, including (1) the use of a photodiode and associatedphotodetector (and transconductance amplifier) to provide a relativelylinear measurement of the output of the medical device, (2), the use ofan inductive current loop with an associated cutout in the circuit boardof the protection apparatus to accept a receiving inductive pickup loop,e.g., connected to an oscilloscope or the like, to measure the output ofthe medical device, (3) the use of an inductive current loop with anassociated cutout in the circuit board of the protection apparatus toaccept a transmitting inductive current loop driven by an external pulsegenerator or the like to provide an input signal, e.g., a simulatedneuro-muscular signal, and thus allow the sense circuitry of the medicaldevice to be tested, etc. These techniques may be used in variouscombinations but what is significant is that they all providetest/measurement capabilities while the medical device is still withinits sterile delivery package, e.g., a pouch.

FIG. 11 shows an isometric view of circuit board 72 and O-ring mountingapparatus of FIGS. 10A and 10B, additionally including a photodiode 220(also see FIG. 12) for emitting nonvisual, e.g., ultraviolet orinfrared, radiation (light) that can be externally monitored to test thefunctionality of the medical device 20, e.g., while it is still within asterilized delivery package, e.g., a pouch. As shown in FIG. 15, anexternal monitor/generator 222 may include a photodetector 224 that issensitive to nonvisual radiation 226 emitted by the photodiode 220. Whenthe photodetector 224 is used in combination with a transconductanceamplifier 228 or the like, the nonvisual radiation 226 which wasgenerated in an essentially linear relationship with the current passedthrough the photodiode 224 is converted to an output signal 230 whichessentially linearly corresponds to the output of the medical device 20through its electrodes 32, 34. This output signal 230 may then bemeasured with an oscilloscope, automated test equipment, or the like, toconfirm that the medical device 20 is performing within specifications(before implantation).

FIGS. 13A and 13B show the presence of a current loop path 232 (alsoshown in FIG. 12) with a cutout 234 for allowing an inductive pickuploop e.g., an oscilloscope probe loop (not shown), to pass through andthus inductively measure the current being passed between electrodes 32,34 of the medical device 20 (via connective surfaces 202, 204 andfeedthrough/back side connection path 238. Optionally, a resistorelement 240, e.g., on the order of 250 ohms, is used to simulate bodytissue and to avoid/limit interactions with LEDs 120, 122. Also, seeFIG. 15 where photodiode 220 is essentially replaced by a short circuitand monitor/generator 222 measures/detects the operation of medicaldevice 20 through inductive pickup loop 236.

FIGS. 14A, 14B, and 14C respectively show top, side and bottom views ofthe embodiment of FIGS. 13A and 13B sealed within a sterile pouch 242having a compliant, and thus somewhat smaller cutout 244 formed thereon.An inductive pickup loop, such as an oscilloscope probe loop (notshown), may thus pass through sterile pouch cutout 244 which in turn iswithin cutout 234, without breaking the sterile seal of pouch 242.

Ideally, however, the LEDs 120, 122 are not present when the currentloop path 232 is used. Accordingly, an optional breakaway portion path246 may be implemented on the circuit board 72 to permanently disconnectthe LEDs 120, 122 when they are no longer needed. Thus, in this mode theLEDs 120, 122 would be used as an initial “go/no go” test and then, as afinal before implantation test, the LEDs 120, 122 would be disconnectedvia breakaway portion path 246 before final measurement testing viacurrent loop path 232. Alternatively, a single pole double throw (SPDT)switch 248 could be used to alternatively enable LEDs 120, 122 orcurrent loop path 232 (see FIG. 15). Such a switch could either be adiscrete device soldered to the circuit board 72 or could be one or moremetallic appendages that extend from the circuit board 72 to form one ormore electrical switches to create the functional equivalent of switch248.

As an additional alternative (see FIG. 15), a pair of capacitive plates250, 252 coupled to the monitor/generator 222 could be used to detectoperation of the medical device 20. Alternatively, capacitive plates250, 252 could be replaced with one or more coils or a surrounding coilto similarly detect operation of the medical device 20. In such a case,element 240 may be replaced with an inductor. Since such alternativeswould tend to block passage of an RF signal into the medical device(needed for RF powered stimulators), this alternative is best used witha battery powered stimulator.

Finally, the previously referenced implantable medical devices (see, forexample, U.S. Pat. Nos. 6,164,284; 6,185,452; 6,208,894; 6,315,721; and6,472,991) may also be able to operate as a sensor and thus senseneuro-muscular signals via its electrodes 32, 34. To test functionalityof such devices operating as a sensor, one must provide an electricalsignal to electrodes 32, 34 and communicate (typically via an RF signal)with the medical device 20 to confirm proper detection of the inputvoltage signal. In this mode (see FIG. 15), the monitor/generator 222operates as a pulse generator and puts out various programmablefrequency and amplitude signals through pickup loop 236 which isinductively provided through current loop path 232 to electrodes 32, 34of the medical device 20. In response, medical device 20 communicateswith controller 164 to determine functionality of the medical device 20.Optionally, controller 164 may communicate with monitor/generator 222(shown as a dashed path) to coordinate comparisons of the expected andactual received signals.

In the previously shown examples, e.g., FIGS. 10A, 11, and 13, theconnective surfaces are shown as solid plated surfaces. Thisconfiguration can result in heating of the connective surfaces and someloss of the magnetic/electromagnetic signals being sent to theimplantable device 20 from power source 160 and/or controller 164 (seeFIGS. 8 and 15), e.g., resulting from eddy currents on the connectivesurfaces, when the implantable medical device 20 is held by theprotection apparatus 70 (and in particular 70′ [see FIGS. 10A AND 10B],70″ [see FIG. 11] or 70′″ [see FIGS. 13A and 13B]). Accordingly, FIGS.16A-16D are alternative embodiments of that previously shown, e.g., inFIG. 10A, wherein the connective surfaces are formed with slots orserpentine paths to reduce eddy currents and thereby reduce signal lossto the implantable medical device 20 of the magnetic and/orelectromagnetic signals while it is held by the protection apparatus 70.In particular, FIGS. 16A and 16B show connective surfaces 202′ and 204′formed as comb-shaped connective surfaces having a plurality of slots260 to minimize eddy currents. Alternatively, FIGS. 16C and 16D showconnective surfaces 202″ and 204″ formed from serpentine paths thatsimilarly form slots 260 in the surface to minimize eddy currents.

Although a specific embodiment of the invention has been described, itis recognized that variations and modifications will readily occur tothose skilled in the art coming within the intended spirit and scope ofthe present invention as defined by the appended claims. For example,while the aforedescribed apparatus 70 shown in FIG. 4 is particularlysuited for use with the exemplary small, cylindrical device of FIG. 1,the present invention includes the use of the aforedescribed protectioncircuitry with other differently shaped medical devices having two ormore electrodes. In such cases, the mounting means would be adjustedaccordingly to accommodate the particular device. In particular, theO-ring embodiments of FIGS. 9A, 9B, 10A, 10B, 11, 13A, 13B, 14A, 14B and14C are particularly adapt at retaining non-cylindrical, e.g., square,triangular, hexagonal, etc., shaped medical devices in the protectionapparatus of the present invention. Additionally, it should be notedthat while current loop path 232 is shown graphically as a single loop(see, e.g., FIG. 13A), this is primarily to simplify the graphicaldepiction of this path and embodiments are intended to also includemulti-looped paths. Advantageously, multi-looped embodiments willfacilitate transmission and/or reception of inductively radiatedsignals. Finally, it is noted that a negative capacity preamp, i.e., anamplifier having a capacitor for negative feedback, could be used withinthe monitor/generator to pick up an electrostatic signal from themedical device and/or the medical device/protection apparatuscombination and thus detect/monitor the operation of the medical device.

1. In combination with a medical device configured to be implanted in apatient's body and an external monitor/generator for functionallytesting the medical device, the medical device including a housingcontaining electronic circuitry having output and input capabilityconnected to first and second electrodes extending exteriorly from thehousing, an apparatus for use with the medical device prior to it beingimplanted, said apparatus comprising: a dielectric substrate carryingspaced first and second connective surfaces, each of said connectivesurfaces being configured to electrically contact one of the electrodesof the medical device; at least one connection element comprising atleast one O-ring for retaining the first and second electrodes of themedical device in physical and electrical contact with said first andsecond connective surfaces; a test/protection circuit carried by saidsubstrate electrically connected between said first and secondconnective surfaces, wherein said test/protection circuit is selectedfrom the group of: (a) a current loop suitable for inductively radiatinga variable magnetic field corresponding to current flowing between thefirst and second electrodes of the medical device, wherein said magneticfield is detectable by the external monitor/generator to therebyfunctionally test the output capability of the electronic circuitry ofthe medical device; (b) at least one diode to emit light correspondingto current flowing between the first and second electrodes of themedical device, wherein the light is detectable by the external monitorgenerator to thereby functionally test the output capability of theelectronic circuitry medical device; (c) a current loop suitable forinductively receiving a variable magnetic field generated by theexternal monitor/generator to thereby functionally test the inputcapability of the electronic circuitry of the medical device; and (d)oppositely directed first and second diodes to thereby serve to protectthe medical device from electrostatic discharge prior to implantation;and wherein said apparatus is configured to be separated from themedical device before implantation.
 2. The apparatus of claim 1 whereinsaid at least one connection element comprises first and secondconductive clips mounted on said dielectric substrate for capturing andretaining the first and second electrodes of the medical device.
 3. Theapparatus of claim 1 wherein said at least one O-ring is formed ofmedical grade silicone.
 4. The apparatus of claim 1 wherein said atleast one connection element comprises a single O-ring and saiddielectric substrate comprises a circuit board that includes a pair ofretaining lips for capturing the single O-ring and wherein the medicaldevice is retainable between the single O-ring and said circuit board.5. The apparatus of claim 1 wherein said dielectric substrate is acircuit board is formed of polyimide.
 6. The apparatus of claim 1wherein said diode is a photodiode suitable for emitting nonvisual lightin response to current therethrough.
 7. The apparatus of claim 1 whereinsaid dielectric substrate has a substrate cutout surrounded by saidcurrent loop to enable an externally provided inductive pickup loop topass through said cutout.
 8. The apparatus of claim 7 additionallycomprising a sterilization pouch wherein said sterilization pouchincludes a pouch cutout conforming to said substrate cutout to enable anexternally provided inductive pickup loop to pass through said substrateand pouch cutouts.
 9. The apparatus of claim 1 additionally comprisingselection means for selecting and/or deselecting a desiredtest/protection circuit.
 10. The apparatus of claim 1 wherein said firstand second connective surfaces are formed to minimize eddy currents. 11.The apparatus of claim 10 wherein said first and second connectivesurfaces are comb-shaped.
 12. The apparatus of claim 10 wherein saidfirst and second connective surfaces are formed from serpentine paths.13. A method of functionally testing an implantable medical device priorto implantation, the device comprising a housing containing electroniccircuitry connected between first and second electrodes extendingexteriorly from the housing, said method comprising: providing first andsecond contacts on a substrate for electrically contacting the first andsecond electrodes; providing at least one connection element forretaining the first and second electrodes of the medical device inphysical and electrical contact with said first and second contacts;providing a current loop path between said first and second contactssuitable for emitting a remotely detectable signal corresponding tocurrent flowing between the first and second electrodes of the medicaldevice; and wherein said apparatus is configured to be separated fromthe medical device before implantation.
 14. The method of claim 13wherein the step of providing a current loop path between said first andsecond contacts is selected from the group of: (a) providing a currentloop between said first and second contacts suitable for inductivelyradiating a variable magnetic field corresponding to current flowingbetween the first and second electrodes of the medical device, whereinsaid magnetic field is detectable by an external monitor/generator tothereby functionally test the output capability of the electroniccircuitry of the medical device; (b) providing at least one diodeelectrically connected between said first and second contacts to emitlight corresponding to current flowing between the first and secondelectrodes of the medical device, wherein the light is detectable by anexternal monitor generator to thereby functionally test the outputcapability of the electronic circuitry medical device; and (c) providinga receiving current loop between said first and second contacts suitablefor inductively receiving a variable magnetic field generated by anexternal monitor/generator to thereby functionally test the inputcapability of the electronic circuitry of the medical device.
 15. Themethod of claim 13 further including the steps of: providing asterilization pouch; placing the device within the sterilization pouch;and sterilizing the device while in said sterilization pouch.
 16. Themethod of claim 15 further including the steps of: forming said currentloop path on said substrate having an inner cutout; providing asterilization pouch having an outer cutout conforming to said innercutout; placing the device within the sterilization pouch; wherein saidconforming inner and outer cutouts enable an externally providedinductive pickup loop to pass therein and provide a signal to anexternally provided monitor; and sterilizing the device while in saidsterilization pouch.
 17. The method of claim 13 further including:applying an activation signal to the device while in said shippingcontainer; and monitoring the emissions corresponding to the medicaldevice in response to the application of said activation signal whereinthe monitoring step is selected from the group of: monitoringinductively coupled magnetic emissions; monitoring visual lightemissions; monitoring nonvisual light emissions; monitoringelectrostatic emissions; monitoring electromagnetic emissions; andmonitoring capacitive changes.
 18. The method of claim 17 wherein saidstep of applying an activation signal comprises providing wirelesscommunicating energy to the electronic circuitry in the housing.
 19. Themethod of claim 17 wherein said step of monitoring the emissions inresponse to the application of said activation signal comprises use of anegative capacity preamp to pick up a signal from the medical device.20. The method of claim 13 wherein the step of providing first andsecond contacts includes forming said contacts to minimize eddycurrents.
 21. The method of claim 20 wherein the step of forming saidcontacts to minimize eddy currents comprises forming said contacts in acomb-shaped manner.
 22. The method of claim 20 wherein the step offorming said contacts to minimize eddy currents comprises forming saidcontacts in a serpentine manner.